Method of repairing and for preventing cracks in metal castings



Oct. 24, 1944. 2,361,106

METHOD OF REPAIRING AND FOR PREVENTING CRACKS -IN METAL C-ASTINGS Filed Nov. '4, 1940' P ate Oct. 24, 194

UNlTED rsmss; PATENT O'FFICEJI rnrrnon REPAIRING. AND FOR. rim

. vaiv'rmo omens IN} METAL CASTINGS Charles :A. Jensen, Inglewood, Calif. Application November '4, 1940, Serial No; 364,204 3 Claims. (Cl. 29-148) My invention relates to a method of repairingcracks in metal castings and for preventing cracks that may develop in castings and particucylinder block with arrows indicating the approximate position of the lines of. 'force ina larly weakened portions thereof or portions that p are subject to extreme variations of temperature, for instance, the cylinder blocks and heads of internal combustion engines, Diesel engine heads, and the like, .and the methods herein disclosed arej an improvement on the 'method of repairing cracks in metal castings patented by me February 5, 1935, Pate'ntNo. 1,989,695.

The principal objectsof my invention areito generally improve upon and simplify the method disclosed in my aforesaid patent, as well as other similar methods, and further, to provide a relatively simple and easily practiced method of repairing cracks in metal castings and for preventing the development of cracks in metal castings,

shrunken portion 0! the block between. the piston chamberan'ci exhaust valve portv and which portion. is generallyreierred to. as a ;hot spotdue to the extremely high temperatures developed by the exhaust gases in passingfrom the. piston chamber to the exhaust port. 1

Fig. 6 is a plan view similar to Fig. 5 and-showing the metal in the hot spot expanded by an inserted pin orplug so as tomaterially strength- I an the metal in this particular portion of the casting and counteract tendency to crack.

\ Fig. 7 is a plan view of a portion of a casting having a crack that hasbeen repaired-in accordance with my improvedmethodand the metal which method involves the following essential steps, namely, the closing of the crack in a ing of holes alongor adjacent the crack, the insertion of a sealing material in the cracks and holes, the insertion of tapered pins or plugs into the drill holes, the inner portions of which pins extend into the cooling fluid circulation chamber or chambers within the casting by peening the metal along or adjacentthe edges of the crack or by connecting the edges of the orack'by brazing or welding.

My invention contemplates the practicing of V casting by the use of-tie .rodsyor bolts, the drillany one, two, or more of the steps just set forth a I and further, any one, two, or more steps of the method may be utilized for preventing the development of cracks in weak portions of metal castings or portions that are subjected to extreme variations of temperature, for instance," the metal adjacent the exhaust 'ports of internal combustion engines or the thick sections of metal between the ports of Diesel engine heads.

In the accompanying. drawing:

Fig.v 1 is a top plan view of an .internal cpmbustion engine cylinder block that is reinforced with transverselyv disposed tie bolts and showing cracks that have been repaired in accord ance with my improved method.

i H v Fig. 2 is an enlarged vertical section taken on the line 2-2 of Fig. 1.

Fig. 3 is a plan view of a portion of a cylinder block and showing a crack between a valve port. "and circulation opening repaired in. accordance "with my improved method. p

Fig. 4 is a vertical section taken on 4-4 of Fig. 3. Fig; 5 is a detail plan view of a portion of a the-" im;

beyond the ends of theicrack'having been acted:

increase in length.

upon soasto efiectively counteract tendency to N Fig. 8 is a plan view of a, portion of a cylinder block having a crack closed and sealed in accordance with my method and through the use of a:

single pin or plug. 1

Fig. i is a cross sectiontaken on the li'ne ,9 -9- of Fig. 8.

Fig. 10 is an elevational view of a portion-of a: Diesel enginehead and showing a crack therein repaired in accordance with my improved. method;

Fig. 11 is an enlarged cross section taken on the" Referring by numerals to the accompanying drawing and particularly to the construction villustrated in Figs. 1 and 2, l0.-designatesthe cylinder block of an internal combustion engine having the usual pistonjchambers. ll, exhaust valve ports i2, inlet valve ports l3, and circulation fl uid openings l4 that communicate with the circula-' tion chambers in the'block around the cylinders 1 and the ports. Cracks CI are shown in the'block betweenthe piston chambers and one of the water passages M, a crack-C2 between'one of the exhaust ports. l3 and one of the water passages 4,14, and a crack C3 between one ofv the'piston chambers and one of theexhaust ports;

I plished.

Tapered pins or plugs l' are nowxdriveninto' the tapered-holes so as to expel the sealing compound therefrom andforce the same into the cracks adjacent the plugs, thereby compressing said sealing compound and likewise placing the approximate position as indicated by the arrow heads in Fig. 6. i

In cylinder blocks "hot spots develop near exhaust ports for the reason that the surrounding metal is very much cooler while the engine is in operation. The air and water cooled outersurface functions as a tight band around the spot and as the colder metal has greater strength and stabilityjthe hot spot willbe compressed due to the fact that the metal when heated becomes somewhat softer. The hot spot remains compressed after the engine ceases to operate and has adjacent metal under compressionstrains. The

compression strains produced by driving the ta pered pins into the casting are counter-opposed to the compression strains produced by the bolts [5 and nuts l6, and thus the solidity of the metal in the casting immediately adjacent the crack is greatly increased. The tapered pins or plugs maybe threaded and screwed into the holes in the block and in orderto enhance the cooling effect of the water or other cooling fluid that is circulated through the chambers in theblock' surrounding the piston chambers and ports, the{ length of the inserted pins or-plugs'is'such that their inner portions extend substantial distances into the coolingnuid circulationfchambersas illustrated in Fig; 2. i 1

The'metal in the casting adjacentthe cracks and inserted pins is now brought together by being peened with a hammer or like tool or by brazing or welding the edges-of the metal to each other along the cracks. i In'practicingmy improved method'as just-described, the tie bolts are utilized'to close and maintain the cracks'in closed position before thetaperedpins, plugs or wedges, are inserted,thereby enabling greater wedging pressure to be impressed on the adjacent metal so as to solidify, said metal throughout the cracked area and consequently insuring a perfect seal'after the, work incident to the practicing In Figs. 3 and 4 I have illustrated a crack between anexhaust valve and a water passage sealed by meansof asingle tapered pinor'plug and v with the sealing compound driven-into the crack undercompression, and in Fig. -'3 arrow heads show the direction of the lines: of compression developed by the driving of the pin 'into the casting, thus solidifying the entire area of metal betweenathe openings and providing an'eflective seal. Thus the wedging action of the inserted pin or plug reverses the lines offorce in the casting.

particularly it the crackoccurs in a hot spotor an area that is subjected to a wide range of temperatures and such practice is very eifective in both old and new engines regardless of whether they are cracked or not. 7

In Fig; 5 I have illustrated a portion of a cylinder block having a piston chamber l8 and an ex-' haust port l9, withaniintervening hot spot or area; that is subjected to extreme temperatures, with arrow heads showing the approximate posi of themethod has been accoin become cool. The compressed "spot now occustarting and stopping of the engine increases these strains until the metal parts or cracks and such "condition is very frequently found in old engines between the valve ports or between the valve ports and the piston chambers.

Thus my improved method can be carried out at the point where these cracks are liable to develop and consequently the method is particularly efiective and has the added advantage of preventing cracks in metal castings at the points where cracks are liable to occur.

The driving of a round wedge such as a tapered pin into the tapered hole in the "hot spot of a cylinder block causes compression of the metal immediately adjacent the wedge and the devel-'- in use and it will also be noted that if this condition is created in a new engine cylinder block, it will materially increase its life or period of usefulness. j j

"Hot spots generally develop adjacent exhaust valvefseats with the resulting action of swelling or expanding one side of tlie'seat, which prevents proper seating of the valve and reduces compres sion. Hot spots? alsocause shrinkageof the adjacent cylinder wall.

By my improved method, the temperature changes inthe hot spot? are materially reduced by extending the'tapered pins, plugs or wedges,

into the cooling medium that circulates through the block, thus counteracting tendency of the;

ficial due to the removal of the pulling strains.

still in the metal immediately adjacentthe crack orfracture. The crack is finally sealed by placing sealing material therein or by drawing its 7 edges'together by peening'or calking.

tion of the lines of force in the metal throughout the .hot spot area and adjacent metal. a

- To fortify and materially increase the resistance to cracking in this hot spot" area, a tapered pin or plug such as" is'driven into a tapered hole the lines of forcein that portion 0! the metal in the hot spot" so that such lines of force take the In the'event that it becomes necessary to prevent parallel movement of the metal adjacent the crack, a threaded tapered pin or plug in a threaded tapered hole is utilizedto create the necessary pressure and after such pressure is developed, a solid row of pipe plugs may be used or sealing material may be calked into the .crack where the metal is very thin.

adjacent the crack, may be used and flat or othershaped wedges may be used to change the direc- Under' certain conditions all three sealingcastings. Where a crack in a casting exists, ta-T pered holes are drilled along the crack'and tapered pins or plugs such as M are driven into said holes so as to compress and thereby strengthen the metal adjacent the crack and which action may slightly widen the crack particularly at the ends thereof.

In some instances it may be found desirable to bore the tapered pin or plug receiving holes in the casting near the ends of the .crack to the sides thereof.

I The second step in this method is to remove the tension and tendency in the metal to pull apart near the ends of the crack so as to prevent extension thereof and this is done by compressing or peening the metal beyond the ends of the crack, the areas of such compression or peening being substantially V-shape with the wide por tions thereof disposed adjacent the ends of the crack so as to taper off the strains impressedin the metal outwardly from the crack. Finally the crack is closed by the insertion of a sealing compound and the peening of the edges of the metal immediately adjacent the crack or by brazing or welding.

Obviously, the method just described may be utilized for preventing cracks in new castings at points or areas where the development of cracks might be expected.

, A variation of the method just described would be to first peen the metal beyond the ends of the crack and afterwards drill, the holes along or adjacent the crack for the receptionof the tapered pins or plugs.

Where my improved method is utilized'for preventing cracks in metal, castings; the casting strains developed by a hot spot" are reversed and the inserted pins that extend into the cooling fluid circulation chambers are highly effective in absorbing theheat normally existing in the hot spots and spreading opposite tension around the spot" and which advantageous result is enhanced by the peening or hammering of the metal adjacent the cracker hot spot."

.Thus my improved method involves the devel:

ing material and without peening or brazing the metal along the'edges of'the crack. H

In Figs. 10-and 11 I have illustrated the repair of a Diesel engine head in accordance with my invention.

The thick sections between the ports of Diesel engine heads become extremely hot due to the ex.- tremely high compression and the cooling efl'ect of the circulation fluid is reduced on account of its being so far from the combustion chamber due to the great thickness of the metal. Under such conditions cracksform, generally between the valve chamber 23 and the injector port 24. A- hole 25 is drilled into the metal between the chamber 23 and injector port 24. which hole intersects the crack and a pin or plug 26 is driven into said hole so as to eii'ectively stop the gas leak between the port and valve chamber. ,In-

clined holes 21 are now bored in the head from a point directly above the hole 25 and pin 26 and which holes 21 diverge toward their lower ends.

The formation of these holes removes the upper end portion of the inserted pin 26 so that the upper end thereof is wedge-shape in cross section. A pin 28 is driven into one of the inclined holes 21 so that its upper end is slightly below the surface of the metal in which the holes are bored and a third pin 28 is now driven into the other one of the holes ZLwith the upper end of said third pin lying flush with the outer surface of the pins are in direct contact with each other.

opment of an excessive amount of pressure or more than is required to prevent the development of-a crack and a highly beneficial force is stored in castings and which force may be and is drawn on as the engine is operated.

Thus the parting or cracking of the metal in the treated areas is not likely as long as the force installed remains in the metal and such force may be renewed by the insertion of new pins in the casting.

In Figs. 8 and 9 I have illustrated the sealing of a superficial crack'with a single inserted wedgelike member. for instance, a tapered pin or plug, and where such practice is carried out a tapered hole is bored in the metal so that it intersects the crack and a single pin such as 22 is driven into ing said holes .by'using the power of the.

Inasmuch as the inclined pins 28 and 29 extend substantial distances into the cooling fluid circulation chamber in the head, the cooling eflect of the circulating medium is transferred to the upper portion of pin 26 and to the external surface of that portion of the head in which the crackis. located so as to bring about maximum cooling eifects to counteract tendency of warping of the valve seat and at the same time stopping leakage of gas.

Large and heavy castings, for instance, internal combustion engine cylinder blocks and Diesel enigine heads frequently shrink at various points when cooling off after casting and which shrinkingaction develops internalcasting strains and wedgein the areas having these internal strains, the latter are relieved with the result that the. life or periods of usefulness of the treated castings are materially increased. g g

Thus it will be seen that I have provided a relatively simple .and easily practiced method for repairing cracks in metal castings and which method may be used with equal advantage in preventing the development of cracks in castings by the strengthening and reinforcement of those parts of the castings where cracks are liable to develop. f

I claim as my invention L 1. The method of" repairing cracks. in metal castings which consists in placing the casting under compression strains applied to said casting at points on opposite sides of the crack therein, so

that the lines of compressive forces are directed fromboth sides toward said casting crackicom pressing the metal in the casting beyond the ends of said-crack, the areas of which compression taper away from said crack in approximate longitudinal alignment therewith, then formingholesfl v in said casting along the crack therein, then'fillwith a sealing compound, then applying pressure to said sealing compound so as to, force same into those portions of the crack between ssid'holes and then uniting the edges orso that the lines of compressive force are directed from both sides toward the crack compressing substantially triangular. areas of metal in castin beyond the ends of sald'crack, with the bases-oi said triangular aress disposed substantially at right angles to the linear position of said crack, then forming holes in said casting along the crack assume therein, then filling said holes with a sealing compound and driving tapered pins into said holes to torceand compress the sealing compound therefrom into those portions of the crack betweensfaid holes and at the same time compressing: and solidifying the metal in the casting adiecent said holes.

3. The method of repairing metal cracks in metal castings as set forth in claim 2 and then connecting the edges of the surface of the metal throughout the length of the crack so as to confine the compressed sealing compound within said crack.

CHARLES A. JENSEN. 

